This invention relates to exercise equipment, more particularly self-contained exercisers for individual use that do not require special facilities, anchoring or the like. The present invention is compact, light-weight and portable, thus convenient for everyday use, even while traveling.
There are three forms of exercise utilizing forces to exercise the muscles of the body, namely, 1) eccentric forces, wherein the muscles move an object away from the body; 2) concentric forces, wherein an object is moved toward the body; and 3) isometric forces, wherein the muscles exert force against a static object. Utilizing these three types of exercise, nearly all the muscles of the body can be toned and conditioned. It is desireable to provide an exerciser which utilizes all three forces to exercise muscles in both extension and contraction movements.
The numerous forms of exercise devices in the art utilize weights or springs as the basis for generating exercise forces. One of the best means, however, for generating force to exercise various parts of the human body is to employ elastic materials, such as latex surgical rubber tubing, to closely simulate the manner in which tendons, ligaments and muscles stretch and contract. This medium, however, presents some difficulties in forming knots which can be easily removed or retied and heretofore has not been successfully utilized in adjustable exercisers.
Elastic materials assume a smaller cross sectional area when they are elongated. This causes them to slip into tightly formed bends and knots which are difficult to untie when the material resumes its normal relaxed cross sectional dimension. This condition is useful for securely holding a knot when there is no intention to untie the knot but undesirable when the knot must be repositioned. One means to deal with repositioning the knot is to utilize a knotting device to control the spacing of the tightened loops in the knot in order to prevent over tightening of the knot.
U.S. Pat. No. 3,409,014 issued Nov. 5, 1968 to S. G. Shannon utilizes a knotting device to provide secure and speedy ligation during surgical procedures. In Shannon, a three-point knotting clip can be used to secure some materials, and a four-point clip is preferred for other materials. The three-point device disclosed by Shannon is utilized on materials which retain their original cross section when tightened, and the four-point device is utilized for materials which change their cross section when tightened. Shannon describes how the resilient forces of the ligated tissue maintain pressure on the knot to hold it secure, but neither discloses nor suggests how untying the resulting knots is facilitated.
U.S. Pat. No. 4,105,349 issued to Kupperman et al. discloses a knotting clip for tying knots in rope and the like for use in circumstances where a loop is desirable and the knot must be untied without difficulty. The clip disclosed by Kupperman et al. utilizes a reinforced border for strength and pointed projections to prevent slippage of the rope. In use, the rope is securely held against the pointed projections by a loop formed in the rope, whereby slippage is prevented by the projections protruding into and distorting the rope. Kupperman et al. neither suggests nor discloses how the clip could be utilized with elastomeric materials, such as latex rubber tubing, without damage to the material.